Online shoppers made Cyber Monday the biggest Internet sales day in US history.
ComScore

Americans racked up their biggest online spending day in history on Cyber Monday, forking over $1.735 billion to Internet retailers, an 18 percent jump over a year ago.

And it wasn't just on Monday. According to ComScore, Americans spent $23.9 billion online during the first 32 days of the November-December holiday season, up 8 percent over last year.

Those big gains may have come at the expense of merchants who were hoping to cash in during Black Friday and the weekend following Thanksgiving. According to the National Retail Federation, shoppers spent $1.7 billion less during that period than they did a year ago.

But even if that's so, the reductions in spending didn't deter online shoppers. ComScore reported that Internet shopping over the weekend amounted to $1.549 billion, up 34 percent over the weekend following Thanksgiving 2012. And for the five days from Thanksgiving through Cyber Monday, online spending came in at $5.3 billion in the US, up 22 percent over the same period last year.

Among the biggest winners were Amazon.com and eBay, which both saw large sales boosts. According to ChannelAdvisor, Amazon's sales were up 44.3 percent over 2012, and eBay saw its receipts boosted by 32.1 percent.